Internal combustion engines feature exhaust systems that may utilize a combined exhaust gas line, also known as an exhaust manifold, to direct exhaust gas to a turbine. In these systems, production costs, material costs, and/or weight of the turbine can be comparatively high, as the nickel-containing material used for the thermally highly-stressed turbine housing is cost-intensive, especially in comparison to the material, for example aluminum, preferably used for a cylinder head of the engine. Therefore, it would be extremely advantageous if a turbine could be made available which could be produced from a less cost-intensive and/or lighter material, for example aluminum or gray cast iron. In order to achieve such goals, the turbine can be equipped with a cooling facility, which greatly reduces the thermal stress on the turbine and turbine housing, thereby allowing for the use of less thermally resistant materials.
German patent DE 10 2008 011 257 A1 describes a liquid cooling facility for a turbine in the form of a cooling jacket that surrounds a turbine housing. The housing features a shell, so that a cavity into which coolant can be introduced is formed between the housing and the shell arranged at a distance therefrom. However, in such a system, coolant is only able to effectively cool areas in near its flow path, leaving remote areas of the housing to experience limited cooling. Thus, high temperature gradients can occur in the turbine housing, which can lead to material fatigue.
The descending temperature gradient in the housing can be reduced, in some cases, by providing a sufficient number of coolant passages, so that each housing part is located directly adjacent to a coolant passage, or by configuring the coolant passage as a coolant jacket which surrounds the flow channel with the largest possible area. Both measures lead to an equalization of temperature in extensive regions of the housing, but at the same time entail the dissipation of large quantities of heat. It may be borne in mind in this connection that the quantity of heat to be absorbed by the coolant in the turbine can be 40 kW or more, if less thermally resistant materials such as aluminum are used to produce the housing. To extract such a large quantity of heat from the coolant in the heat exchanger and to discharge it into the environment by air flow proves to be problematic.
Although modern motor vehicle drive units are equipped with powerful fan motors in order to make available to the heat exchangers the mass air flow required for a sufficiently large heat transfer, a further parameter which affects heat transfer, namely the surface area made available for the heat transfer, cannot be made of any desired size or enlarged to any desired degree, since the space available in the front end region of the vehicle, where the different heat exchangers are generally arranged, is limited.
Against the background of what has been said above, it is the object of the present disclosure to make available an internal combustion engine comprising at least one cylinder, formed from at least one cylinder block and at least one cylinder head and at least one turbine within a turbine housing. The engine is optimized with regard to cooling of the turbine, by each cylinder having at least one exhaust opening for discharging exhaust gases from the cylinder and an exhaust gas line being connected to each exhaust opening, the exhaust gas lines converging to produce at least one combined exhaust gas line forming at least one exhaust manifold, the combined exhaust gas line opening into the at least one turbine within the turbine housing; the turbine having at least one flow channel conducting exhaust gas through the turbine housing, and at least one coolant passage integrated in the housing in order to form a cooling facility; and at least one chamber being arranged between the at least one coolant passage and the at least one flow channel conducting exhaust gas.
With this structure, the turbine housing can be effectively cooled evenly, allowing it to be constructed from less expensive and/or lighter materials. In one example, the multiple coolant passages enables the coolant to reach remote areas of the housing, reducing the overall temperature of the housing and ensuring that large quantities of heat is not dissipated in one area (to reduce potential for boiling). In addition, the chambers that are arranged between the coolant passage and the flow channel in one embodiment create gaps that serve to shield areas from heat transfer, and ribs that serve to connect coolant passages to the areas that need cooling, thereby directing heat flow in a predetermined manner. In this way, heat flow can be controlled more effectively than prior systems have allowed, resulting in heat distribution that is customized for a given material and turbine configuration, and the ability to utilize less expensive and/or lighter materials with lower heat tolerances.
Further advantageous details and effects of the internal combustion engine are explained in greater detail below with reference to the configurations illustrated in the figures.